1. Field of the Invention
The present invention relates to an input device that inputs information according an approach state of an object using a change in capacitance or the like, a method of controlling the input device, and a program and, particularly, to an input device that inputs information according to an operation of a finger, a pen, or the like in various information devices such as a computer.
2. Description of the Related Art
Since a sensor that detects a change in capacitance can detect the approach of an object (for example, a finger or a pen) with a simple configuration, the sensor is widely used for user interface devices of various electronic devices, such as touch pads of notebook type computers or touch panels of smart phones.
In International Publication No. WO 2012/117437, a touch panel device including a touch panel unit in which a plurality of electrodes are arranged is described. A scan electrode is determined from among the plurality of electrodes of the touch panel unit, and the touch panel unit is operated for the determined scanning electrode. Accordingly, a measurement value reflecting a change in capacitance of each electrode is acquired, and it is detected whether the touch panel unit is touched based on the acquired measurement value.
However, since such an input device is required to sensitively detect the approach of an object a detection surface of a sensor, there is a problem in that the sensor is particularly susceptible to external electromagnetic noise. For example, in the case of the above-described capacitive sensor, since a change in capacitance of an electrode caused by the approach of an object is detected as a small change in the amount of charge, there is a problem in that erroneous detection of coordinates or a contact state of an object easily occurs due to an influence of noise.
In the input device, it is desirable to reduce the influence of noise as much as possible, but it is not easy to minimize the influence of noise in a detection step. On the other hand, there is a certain range of prediction of data that is acquired by the sensor. For example, since a position of a finger moves to draw a certain trajectory, it is difficult for a trajectory of the finger to be considered in a case in which an extreme change is drawn. Based on this tendency of the data, it is required to reduce the influence of noise.